Stent with Improved Flexibility

ABSTRACT

A stent comprises a plurality of connected serpentine circumferential bands. Adjacent serpentine circumferential bands are connected via a plurality of longitudinal connectors extending between peaks on one serpentine circumferential band and troughs on the serpentine circumferential band adjacent thereto. The struts of the serpentine bands are arranged such that on expansion of the stent, peaks and troughs which are substantially circumferentially aligned with one another, but not connected with one another, on adjacent serpentine circumferential bands are circumferentially displaced from one another.

BACKGROUND OF THE INVENTION

Stents are placed or implanted within a variety of bodily vesselsincluding in coronary arteries, renal arteries, peripheral arteriesincluding illiac arteries, arteries of the neck and cerebral arteries,veins, biliary ducts, urethras, fallopian tubes, bronchial tubes, thetrachea, the esophagus and the prostate.

Stents are available in a wide range of designs. One popular stentdesign includes a plurality of serpentine rings having alternating peaksand troughs. Adjacent rings are interconnected via connecting elements.If adjacent rings are spaced too close together, however, binding,overlapping or interference can occur between adjacent rings on theinside of a bend due to the facing peaks and troughs moving toward eachother and into contact.

There remains a need for innovative, flexible stents which are designedso that interference between adjacent rings does not substantiallyoccur.

Without limiting the scope of the invention a brief summary of some ofthe claimed embodiments of the invention is set forth below. Additionaldetails of the summarized embodiments of the invention and/or additionalembodiments of the invention may be found in the Detailed Description ofthe Invention below.

A brief abstract of the technical disclosure in the specification isprovided as well for the purposes of complying with 37 C.F.R. 1.72.

All U.S. patents and applications and all other published documentsmentioned anywhere in this application are incorporated herein byreference in their entirety.

SUMMARY OF THE INVENTION

In one embodiment, the invention is directed to a stent comprising atleast two serpentine circumferential bands including a first serpentinecircumferential band and a second serpentine circumferential band. Eachserpentine circumferential band has alternating peaks and troughs. Thereis a plurality of unconnected peak-trough pairs with each unconnectedpeak-trough pair comprising a peak on the first serpentinecircumferential band and a trough on the second serpentinecircumferential band which is substantially circumferentially alignedwith the peak when the stent is in an unexpanded configuration anddesirably when it is in a delivery configuration on a catheter. Thetrough is not connected to the peak. There also is a plurality ofconnected peak-trough pairs with each connected peak-trough paircomprising a peak on the first serpentine circumferential band and atrough on the second serpentine circumferential band which issubstantially circumferentially aligned with the peak when the stent isin an unexpanded configuration and desirably when it is in a deliveryconfiguration on a catheter. The trough is connected to the peak. Thedistance along the first serpentine circumferential band between eachpeak of a connected peak-trough pair and an adjacent peak of anunconnected peak-trough pair differs from the distance along the secondserpentine circumferential band between the trough of theconnected-trough pair and an adjacent trough of an unconnectedpeak-trough pair, the adjacent peak substantially opposite the adjacenttrough. As the stent expands, peaks and troughs of unconnectedpeak-trough pairs are displaced relative to one another about thecircumference of the stent.

Desirably, the first and second serpentine circumferential bands areconnected to one another via a plurality of longitudinal connectors.

Typically, the stent will have three or more of the serpentinecircumferential bands, adjacent serpentine circumferential bandsconnected one to the other. There will be a plurality of unconnectedpeak-trough pairs along adjacent serpentine circumferential bands, eachunconnected peak-trough pair comprising a peak on one serpentinecircumferential band and a trough on the adjacent serpentinecircumferential band which is substantially circumferentially alignedwith the peak when the stent is in an unexpanded configuration, anddesirably in a delivery configuration on a catheter, the trough notconnected to the peak. There will also be a plurality of connectedpeak-trough pairs along adjacent serpentine circumferential bands, eachconnected peak-trough pair comprising a peak on one serpentinecircumferential band and a trough on the adjacent serpentinecircumferential band which is substantially circumferentially alignedwith the peak when the stent is in an unexpanded configuration, anddesirably in a delivery configuration on a catheter, the troughconnected to the peak. The distance along a serpentine circumferentialband between each peak of a connected peak-trough pair and an adjacentpeak of an unconnected peak-trough pair differs from the distance alongthe adjacent serpentine circumferential band between the trough of theconnected-trough pair and an adjacent trough of an unconnectedpeak-trough pair, the adjacent peak substantially opposite the adjacenttrough.

The invention is also directed to a stent, comprising a plurality ofserpentine circumferential bands comprising alternating peaks andtroughs. Adjacent serpentine circumferential bands are connected to oneanother. The serpentine circumferential bands include a first serpentinecircumferential band, a second serpentine circumferential band and athird serpentine circumferential band. The first serpentinecircumferential band includes high peaks and low peaks. The secondserpentine circumferential band includes high peaks and low peaks, hightroughs and low troughs. The third serpentine circumferential bandincludes high troughs and low troughs. The high peaks of the firstserpentine circumferential band are substantially circumferentiallyaligned with the low troughs of the second serpentine circumferentialband and the low peaks of the first serpentine circumferential band aresubstantially circumferentially aligned with the high troughs of thesecond serpentine circumferential band. Also the high peaks of thesecond serpentine circumferential band are substantiallycircumferentially aligned with the low troughs of the third serpentinecircumferential band and the low peaks of the second serpentinecircumferential band are substantially circumferentially aligned withthe high troughs of the third serpentine circumferential band.Desirably, the first serpentine circumferential band is interlaced withthe second serpentine circumferential band and the second serpentinecircumferential band is interlaced with the third serpentinecircumferential band.

Desirably, adjacent serpentine circumferential bands are connected toone another via a plurality of longitudinal connectors extending betweensubstantially circumferentially aligned peaks and troughs.

Typically, there will be a plurality of unconnected peak-trough pairs,each unconnected peak-trough pair comprising a peak on a serpentinecircumferential band and a trough on the serpentine circumferential bandadjacent thereto which is substantially circumferentially aligned withthe peak when the stent is in an unexpanded configuration, and desirablyin a delivery configuration on a catheter, the trough not connected tothe peak. There will also be a plurality of connected peak-trough pairs,each connected peak-trough pair comprising a peak on a serpentinecircumferential band and a trough on the serpentine circumferential bandadjacent thereto which is substantially circumferentially aligned withthe peak when the stent is in an unexpanded configuration, and desirablyin a delivery configuration on a catheter, the trough connected to thepeak. The distance along the serpentine circumferential band betweeneach peak of a connected peak-trough pair and an adjacent peak of anunconnected peak-trough pair differs from the distance along theadjacent serpentine circumferential band between the trough of theconnected-trough pair and an adjacent trough of an unconnectedpeak-trough pair, the adjacent peak substantially opposite the adjacenttrough.

As the stent expands, peaks and troughs of unconnected peak-trough pairsare displaced relative to one another about the circumference of thestent.

The invention is also directed to a stent having a proximal end and adistal end comprising a plurality of connected serpentinecircumferential bands. Each serpentine band comprises a plurality ofstruts arranged in alternating peaks and troughs. Adjacent serpentinecircumferential bands are connected via a plurality of longitudinalconnectors extending between peaks on one serpentine circumferentialband and troughs on the serpentine circumferential band adjacentthereto. The struts of the serpentine bands are arranged such that onexpansion of the stent, peaks and troughs which are substantiallycircumferentially aligned with one another, but not connected with oneanother, on adjacent serpentine circumferential bands arecircumferentially displaced from one another. Typically, each bandcomprises a repeating pattern of three or more struts of differentlengths. The struts of different lengths are also typically of differentwidths. Desirably, the stent is constructed and arranged to beself-expanding.

The invention is also directed to a stent comprising at least onecircumferential serpentine band disposed about a longitudinal axis, theserpentine band comprising a plurality of struts, adjacent strutsconnected one to the other, the serpentine band having alternating peaksand troughs, the serpentine band including at least three peaks whichare circumferentially and longitudinally offset from one another.Typically, the stent will comprise a plurality of the circumferentialserpentine band, adjacent circumferential serpentine bands connected toone another. Desirably, adjacent circumferential serpentine bands areconnected to one another via two or more longitudinal connectors. Moredesirably, the stent is constructed such that unconnected peaks andtroughs which are substantially circumferentially aligned prior toexpansion of the stent are circumferentially displaced from one anotheron expansion of the stent.

The invention is also directed to a stent comprising at least oneserpentine circumferential band which comprises a repeat pattern ofthree or more struts of different lengths. Desirably, the stentcomprises a plurality of the serpentine band, adjacent bands connectedto one another. The struts are arranged in a pattern of alternatingpeaks and troughs.

The invention is also directed to a stent comprising at least twoserpentine bands including a first serpentine band and a secondserpentine band, each serpentine band having alternating peaks andtroughs, the first serpentine band including connected peaks andunconnected peaks, the second serpentine band including connectedtroughs and unconnected troughs. The peaks of the first serpentine bandare substantially longitudinally aligned with the troughs of the secondserpentine band when the stent is in an unexpanded state, and desirablyin a delivery configuration on a catheter. The connected peaks areconnected to the connected troughs with connectors, each of theconnectors having two ends which are substantially circumferentiallyaligned with one another in an unexpanded state, and desirably in adelivery configuration on a catheter. The unconnected peaks of each bandbecome circumferentially displaced from the unconnected troughs of anadjacent serpentine circumferential band, and the unconnected troughs ofeach serpentine circumferential band become circumferentially displacedfrom the unconnected peaks of each serpentine circumferential band onexpansion of the stent.

The invention is also directed to a stent comprising at least twoserpentine bands including a first serpentine band and a secondserpentine band. Each serpentine band has alternating peaks and troughs.The first serpentine band includes connected peaks and unconnectedpeaks, and the second serpentine band includes connected troughs andunconnected troughs. The first and second serpentine bands have anidentical number of peaks. The peaks of the first serpentine band aresubstantially longitudinally aligned with the troughs of the secondserpentine band when the stent is in an unexpanded state. The connectedpeaks are connected to the connected troughs. The unconnected peaks ofeach band become circumferentially displaced from the unconnectedtroughs of an adjacent band, and the unconnected troughs of each bandbecome circumferentially displaced from the unconnected peaks of anadjacent band on expansion of the stent.

Desirably, the stent comprises a third serpentine band havingalternating peaks and troughs. The first, second and third serpentinebands are arranged sequentially along the stent with the firstserpentine band and the second serpentine band connected one to theother and defining a plurality of cells therebetween and the secondserpentine band and the third serpentine band connected one to the otherand defining a plurality of cells therebetween. The first, second andthird serpentine bands have the same number of peaks.

More desirably, the stent has a first and second end region and a middleregion extending therebetween wherein at least one of the first andsecond end regions of the stent has a different cell structure from theremainder of the stent. Optionally, the first and second end regions mayhave a cell structure which differs from one another.

Additional details and/or embodiments of the invention are discussedbelow.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 a shows a flat view of an inventive stent.

FIG. 1 b shows a flat view of an inventive stent.

FIG. 1 c shows an enlarged view of a portion of the inventive stent ofFIG. 1 b.

FIG. 2 shows a flat view of an inventive stent.

FIG. 3 shows a flat view of an inventive stent.

FIG. 4 shows a flat view of an inventive stent in an unexpandedconfiguration.

FIG. 5 shows a flat view of the stent of FIG. 4 in an expandedconfiguration.

FIG. 6 a shows a flat view of another inventive stent.

FIG. 6 b shows an enlarged end portion of the stent of FIG. 6 a.

DETAILED DESCRIPTION OF THE INVENTION

This invention may be embodied in many different forms. This descriptionis an exemplification of the principles of the invention and is notintended to limit the invention to the particular embodimentsillustrated.

For the purposes of this disclosure, unless otherwise indicated,identical reference numerals used in different figures refer to the samecomponent.

Also, the phrase ‘substantially circumferentially aligned’ as usedherein does not require perfect circumferential alignment. Rather, itrequires that at least a portion of a peak be circumferentially alignedwith a portion of a trough on an adjacent serpentine circumferentialband. Examples of substantially circumferentially aligned peaks andtroughs include but are not limited to facing peak 16′ and trough 18′connected by longitudinal connector 24 shown in FIGS. 1 a, 2 and 3 andfacing peak 16 b′ and trough 18 b 40 connected by longitudinal connector24 shown in FIG. 5, as well as facing peak 16″ and trough 18″ shown inthe circled regions of FIGS. 1-3.

Further, the term ‘longitudinally staggered’ when used in reference topeaks or troughs within a serpentine circumferential band refers topeaks or troughs with the band which extend to different positionslengthwise along the length of the stent. Examples of longitudinallystaggered peaks within a serpentine circumferential band include but arenot limited to peaks 16′ and 16″ within a band as shown in FIGS. 1-3.Examples of longitudinally staggered troughs within a serpentinecircumferential band include but are not limited to troughs 18′ and 18″within a band as shown in FIGS. 1-3. Longitudinally aligned peaks ortroughs extend to the same location lengthwise along the stent. Examplesof longitudinally aligned peaks or troughs are shown in the proximal endand distal ends of the stent of FIG. 2. Other examples include all peaks16′ within a serpentine band.

The term ‘distal’ as used herein in reference to the distal end of astent refers to the end of the stent which is inserted first into thebody. The term ‘proximal’ as used herein in reference to the proximalend of a stent refers to the end of the stent which is inserted lastinto the body. It is within the scope of the invention that theorientation of any of the inventive stents disclosed herein can bereversed so that either end may be delivered into the body first.

In FIG. 1 a, a flat view of an inventive stent is shown. The stent has adistal end 10 and a proximal end 12 and comprises a plurality ofserpentine circumferential bands 20. Each band comprises a plurality ofinterconnected struts and includes struts of three different lengths. Asshown, the first strut 14 a is shorter and narrower than second strut 14b and third strut 14 c. Third strut 14 c is longer and wider that firststrut 14 a and second strut 14 b. The struts 14 a-c are arranged in arepeating pattern such that the circumferentially adjacent peaks 16within each band 20 terminate at different longitudinal points along thestent and the circumferentially adjacent troughs 18 within each band 20terminate at different longitudinal points along the stent.

Adjacent serpentine circumferential bands are connected to one anotherin at least one and desirably, as shown in FIG. 1 a, a plurality oflocations. In the stent of FIG. 1 a, the connections between adjacentserpentine circumferential bands are in the form of longitudinalconnectors 24 which extend between peaks 16 on one band andsubstantially circumferentially aligned troughs 18 on an adjacent band.

Desirably, circumferentially adjacent connectors 20 are separated by apath along one serpentine circumferential band which traverses at leasttwo peaks of the serpentine circumferential band and by a path along theadjacent serpentine circumferential band which traverses at least twotroughs of the adjacent serpentine circumferential band. The inventionallows for more peaks or fewer and/or more troughs or fewer troughsbetween adjacent connectors of any of the embodiments disclosed herein.

The stent is further constructed so that in the unexpandedconfiguration, and desirably in a delivery configuration, peaks of oneserpentine circumferential band are substantially circumferentiallyaligned with troughs of an adjacent serpentine circumferential band.

Because of the unequal strut pair lengths of strut pairs which areopposite one another on adjacent serpentine circumferential bands, onexpansion of the stent unconnected peaks and troughs which weresubstantially circumferentially aligned with one another will bedisplaced circumferentially relative to one another.

In another embodiment of the invention, as shown in the flat in FIG. 1b, adjacent serpentine circumferential bands 20 are interconnected via aplurality of connectors 24 whose first and second ends arecircumferentially and longitudinally offset from one another. Desirably,as shown in FIG. 1 b, connectors 24 are substantially linear. Non-linearconnectors, including curved connectors, connectors having curvedportions and connectors having angled portions, may also used if spacepermits. Connectors 24 may be seen in greater detail in FIG. 1 c whichis an enlargement of a portion of the stent of FIG. 1 b. The connectorsare shown with hatch marks in FIG. 1 c. Although connectors 24 are at anoblique angle relative to the longitudinal axis of the stent, they are,nevertheless, substantially parallel to the longitudinal axis of thestent. It is within the of the invention to provide embodiments in whichconnectors 24 are disposed at a more substantial angle relative to thelongitudinal axis of the stent so that the connectors are notsubstantially parallel to the longitudinal axis of the stent. Theconnectors of FIG. 1 b may also be longer, depending on the separationbetween adjacent serpentine circumferential bands.

In other respects, the stent of FIGS. 1 b and 1 c is similar to that ofFIG. 1 a. Both stents have three types of struts 14 a-14 c of increasinglength and width. Both have connected pairs of peaks and trough 16′ and18′ as well as unconnected pairs of substantially circumferentiallyaligned and unconnected peaks 16″ and troughs 18″. In both stents, thestruts are distributed such that on expansion of the stent, unconnectedbut substantially circumferentially aligned peaks and troughs aredisplaced relative to one another about the circumference of the stent.

In another embodiment of the invention, as shown in the flat in FIG. 2,each serpentine circumferential band comprises three types of struts ofdifferent length, struts 14 a-14 c.

With the exception of the distal-most serpentine circumferential band,within a serpentine circumferential band, the peaks are arrangedcircumferentially in a repeat pattern of two longitudinally alignedadjacent peaks and one shorter peak adjacent to the two aligned peaks.Also, with the exception of the proximal-most serpentine circumferentialband, within a serpentine circumferential band, the troughs are arrangedcircumferentially in a repeat pattern of two longitudinally alignedadjacent troughs and one longer trough adjacent to the two alignedtroughs.

As with the stent of FIG. 1 a, the struts within the serpentinecircumferential bands are arranged such that when the stent is in anunexpanded state, peaks on one band are substantially circumferentiallyaligned with troughs on an adjacent substantially circumferential band.Upon expansion of the stent, peaks and troughs which were substantiallycircumferentially aligned with one another will be displacedcircumferentially relative to one another.

The proximal-most and distal-most serpentine circumferential bands ofthe stent of FIG. 2 differ from that of FIG. 1 a in that the troughs ofthe proximal-most serpentine circumferential band are aligned withanother and the peaks of the distal-most serpentine circumferential bandare aligned with another, unlike in the stent of FIG. 1 a. Moreover, thepeaks in the proximal-most serpentine circumferential band are arrangedin a repeating pattern of two longer peaks followed by one shorter peakand the troughs in the distal-most serpentine circumferential band arearranged in a repeating pattern of one longer trough and two shortertroughs.

The stent of FIG. 2 is similar to the stent of FIG. 1 a in that thenumber of connections between the adjacent serpentine circumferentialbands is constant along the length of the stent. Also, the frequency ofconnections between the adjacent serpentine circumferential bands isconstant along the length of the stent as is the spacing of theconnections about the circumference of the stent.

Another inventive stent is shown in FIG. 3. The stent of FIG. 3 issimilar to the stent of FIG. 2 but differs in that troughs in theproximal-most serpentine circumferential band are not longitudinallyaligned with one another. Also, the peaks in the distal-most serpentinecircumferential band are not longitudinally aligned with one another.Rather, the proximal-most and distal-most serpentine circumferentialbands of the stent are of the same construction as the remainder of theserpentine circumferential bands in the stent.

FIG. 4 shows a flat view of an inventive stent in an unexpandedconfiguration. In this figure the unconnected peaks 16″ of each bandproximal to the distal most band are substantially circumferentiallyaligned with the unconnected troughs 18″ of an adjacent band 20. Thestruts 14 a-c are of three lengths and widths. The stent of FIG. 4 isshown in an expanded configuration in FIG. 5. In the expandedconfiguration, unconnected peaks 16″ and unconnected troughs 18″ whichwere previously substantially circumferentially aligned with one anotherare now displaced circumferentially, relative to one another. A similarcircumferential displacement between unconnected but substantiallycircumferentially aligned peaks and troughs occurs in the other stentsdisclosed herein as well.

An inventive stent with special ends is shown in the flat in FIGS. 6 aand 6 b. Unlike with the stents of the previous figures, the stent ofFIGS. 6 a and 6 b has an increased number of connectors extendingbetween adjacent serpentine circumferential bands at the ends of thestent. Specifically, each peak on the proximal-most serpentinecircumferential band is connected to a trough on the adjacent serpentinecircumferential band and each trough on the distal-most serpentinecircumferential band is connected to a peak on the adjacent serpentinecircumferential band. The connectivity results in plurality of largerand smaller substantially diamond-shaped cells 25 a and 25 b (shown withhatching) which serves to stabilize the end of the stent.

The stent of FIGS. 6 a and 6 b may be modified in numerous ways. In onemodification, only one end of the stent is provided with the additionalconnectors so that only one end of the stent has the large cell/smallcell structure shown in FIGS. 6 a and 6 b. In another modification, atone or both ends of the stent three or more adjacent serpentinecircumferential bands are interconnected with additional or fewerconnectors as compared with the remainder of the stent. Thus, theresulting stent has multiple adjacent rows of large and small diamondcells at one or both ends of the stent. Also, the ratio of connectors topeaks may be other than the 1:1 ratio provided at the end of the stentof FIG. 6 a and other than the ratio of 1:3 provided in FIG. 1 a.

The stent of FIG. 1 a is designed such that the expansion proceeds inthe same way whether the stent is deployed from the proximal to thedistal end or vice versa. The stents of FIGS. 2-6, on the other, expanddifferently depending on whether the stent is expanded from the proximalto the distal end or vice versa.

In the middle serpentine circumferential bands of the stent of FIG. 2,deployment from the distal end 10 of the stent results in the deploymentof the unconnected peaks 16″ of each serpentine circumferential band 20before the deployment of the connected peaks 16′. Deployment from theproximal end 12 of the stent results in the deployment of the connectedtroughs 18′ of each band 20 before the deployment of the unconnectedtroughs 18″.

In the inventive stents disclosed herein, each serpentinecircumferential band is characterized by a path length about theperiphery of the stent. This path length corresponds to the length thatthe band would have if cut open and stretched out into a line.Desirably, as shown in FIGS. 1-6, each of the serpentine circumferentialbands is of the same total pathlength. The invention also contemplatesembodiment in which the serpentine bands are not all of the samepathlength. To the extent that the stent has pathlengths of differentlength, the different length pathways are desirably provided only at oneor both ends of the stent.

In the inventive stents disclosed in FIGS. 1-6, the serpentinecircumferential bands all have the same number of peaks and the samenumber of troughs. Although the invention also contemplates embodimentswhich include bands of different numbers of peaks and troughs, to theextent that such bands are present, it is desirable that they be presentonly at one or both ends of the stent.

To the extent that the stents of FIGS. 1-6 are considered to compriseserpentine circumferential bands, each of which comprises a plurality ofinterconnected struts, it is noted that all of the bands have the samenumber of struts. The invention also contemplates embodiments having thepresence of some serpentine circumferential bands which have more orfewer struts than other of the serpentine circumferential bands.Desirably, however, the bands having different numbers of struts areprovided only at one or both ends of the stent.

The inventive stents may also be considered to compromise a plurality ofinterconnected cells. As shown in FIG. 1 a, the stent comprises aplurality of rows of interconnected cells 27′ and 27″. Cells 27′ and 27″are identical in area and shape but extend in opposite helicaldirections about the longitudinal axis of the stent. Each cell isdefined by first and second paths which are connected to one another byconnectors. Cell 27′ for example, has a first path 31′ and a second path33′ connected by connectors 24. The first path forms a part of aserpentine circumferential band and the second path form a part ofanother serpentine circumferential band. In the embodiment of FIGS. 1-6,the first and second paths at the ends of a cell are of the samepathlength. The first and second paths of a cell also have the samenumber of struts. However, the arrangement of the struts in the firstand second paths differ from one another resulting in peak-trough pairswithin a cell which are substantially circumferentially aligned in anunexpanded state and desirably in a delivery configuration on a catheterand which are circumferentially displaced relative to one another onexpansion of the stent.

In the embodiment of FIG. 1 b, cells 27′ and 27″ are oriented inopposite helical directions about the longitudinal axis of the stent. Inthe embodiment of FIG. 2, three types of cells 27′, 27″ and 27′″ arepresent as a result of the alignment of the peaks at one end and thetroughs at the other end of the stent. In the embodiments of FIGS. 3 and4, only a single type of cell 27′ is present. In the embodiment of FIGS.6 a and 6 b, cells 25 a and 25 b at the ends of the stent aresubstantially diamond shape whereas the remaining cells 27′ are notsubstantially diamond shaped.

The inventive stents of FIGS. 1-6 allow for pairs of unconnected peaksand troughs on adjacent bands to be substantially aligned in anunexpanded state, and desirably in the delivery configuration, whileallowing for the unconnected peaks and troughs to be displacedcircumferentially relative to one another on expansion of the stent.This is achieved, using serpentine circumferential bands of equal pathlength and/or equal numbers of peaks, by arranging the struts of thestent such that the path length between a connected peak and acircumferentially adjacent connected peak on a first serpentine band isdifferent from the path length along an adjacent serpentine band betweenthe corresponding connected trough and the corresponding unconnectedtrough. Differently stated, the summed length of the two strutsimmediately circumferentially adjacent to a connected peak is differentthan the summed length of the two struts immediately adjacent thecorresponding connected trough as the circumference of the stent istraversed in a given direction. By employing bands with the same numberof peaks to achieve the displacement on expansion of the stent, the useof connectors which are substantially angled relative to thelongitudinal axis may be avoided. Moreover, more uniform coverage of thevessel may be achieved as compared with stents having bands of differingnumbers of peaks.

The invention is also directed to a stent having a proximal end and adistal end comprising a plurality of connected serpentinecircumferential bands. Each serpentine band comprises a plurality ofstruts arranged in alternating peaks and troughs. Adjacent serpentinecircumferential bands are connected via a plurality of longitudinalconnectors extending between peaks on one serpentine circumferentialband and troughs on the serpentine circumferential band adjacentthereto. The struts of the serpentine bands are arranged such that onexpansion of the stent, peaks and troughs which are substantiallycircumferentially aligned with one another, but not connected with oneanother, on adjacent serpentine circumferential bands arecircumferentially displaced from one another. Typically, each bandcomprises a repeating pattern of three or more struts of differentlengths. The struts of different lengths are also typically of differentwidths. Desirably, the stent is constructed and arranged to beself-expanding.

The invention is also directed to a stent comprising at least onecircumferential serpentine band disposed about a longitudinal axis, theserpentine band comprising a plurality of struts, adjacent strutsconnected one to the other, the serpentine band having alternating peaksand troughs, the serpentine band including at least three peaks whichare circumferentially and longitudinally offset from one another.Typically, the stent will comprise a plurality of the circumferentialserpentine band, adjacent circumferential serpentine bands connected toone another. Desirably, adjacent circumferential serpentine bands areconnected to one another via two or more longitudinal connectors. Moredesirably, the stent is constructed such that unconnected peaks andtroughs which are substantially circumferentially aligned prior toexpansion of the stent are circumferentially displaced from one anotheron expansion of the stent.

The invention is also directed to a stent comprising at least oneserpentine circumferential band which comprises a repeat pattern ofthree or more struts of different lengths. Desirably, the stentcomprises a plurality of the serpentine band, adjacent bands connectedto one another. The struts are arranged in a pattern of alternatingpeaks and troughs.

The invention is also directed to a stent comprising at least twoserpentine bands including a first serpentine band and a secondserpentine band, each serpentine band having alternating peaks andtroughs, the first serpentine band including connected peaks andunconnected peaks, the second serpentine band including connectedtroughs and unconnected troughs. The peaks of the first serpentine bandare substantially longitudinally aligned with the troughs of the secondserpentine band when the stent is in an unexpanded state. The connectedpeaks are connected to the connected troughs with connectors, each ofthe connectors having two ends which are substantially longitudinallyaligned with one another in at least the unexpanded state. Theunconnected peaks of each band become circumferentially displaced fromthe unconnected troughs of an adjacent serpentine circumferential band,and the unconnected troughs of each serpentine circumferential bandbecome circumferentially displaced from the unconnected peaks of eachserpentine circumferential band on expansion of the stent.

The invention is also directed to a stent comprising at least twoserpentine bands, such as that shown by way of non-limiting example inFIGS. 6 a and 6 b, including a first serpentine band and a secondserpentine band. Each serpentine band has alternating peaks and troughs.The first serpentine band includes connected peaks and unconnectedpeaks, and the second serpentine band includes connected troughs andunconnected troughs. The first and second serpentine bands have anidentical number of peaks. The peaks of the first serpentine band aresubstantially longitudinally aligned with the troughs of the secondserpentine band when the stent is in an unexpanded state. The connectedpeaks are connected to the connected troughs. The unconnected peaks ofeach band become circumferentially displaced from the unconnectedtroughs of an adjacent band, and the unconnected troughs of each bandbecome circumferentially displaced from the unconnected peaks of anadjacent band on expansion of the stent. Optionally, the first andsecond serpentine bands may be of different total pathlength about thestent.

Desirably, as shown in FIG. 6 a, the stent comprises a third serpentineband having alternating peaks and troughs. The first, second and thirdserpentine bands are arranged sequentially along the stent with thefirst serpentine band and the second serpentine band connected one tothe other and defining a plurality of cells therebetween and the secondserpentine band and the third serpentine band connected one to the otherand defining a plurality of cells therebetween. The first, second andthird serpentine bands have the same number of peaks.

More desirably, as shown in FIGS. 6 a and 6 b, the stent has a first andsecond end region and a middle region extending therebetween wherein atleast one of the first and second end regions of the stent has adifferent cell structure from the remainder of the stent. Optionally,the first and second end regions may have a cell structure which differsfrom one another.

The invention is also directed to helical stents. One or more helicalbands may be provided where the peaks and troughs on it are arrangedsuch that some of the peaks are substantially circumferentially alignedand connected to some of the troughs on an adjacent turn of the helicalband or on an adjacent helical band and other substantiallycircumferentially aligned peaks and troughs on adjacent bands oradjacent turns of a band are not connected to one another. On expansionof the stent, the non-connected substantially circumferentially alignedpeaks and troughs are circumferentially displaced from one another. Thismay be achieved with an appropriate arrangement of struts.

Any of the inventive stents disclosed herein may also be provided in a‘jelly roll’ configuration. For example, the flat pattern of FIG. 1 maybe rolled into a tube without securing the longitudinal edges to oneanother. Such a stent would be deployed by unrolling and expansion ofthe cells or bands which extend about the longitudinal axis of thestent. An example of such a stent is disclosed in WO0132099.

The inventive stents disclosed herein may also be provided in anembodiments in which the longitudinal connectors may be shorter orlonger than those shown in FIG. 1 a or any of the other figuresdisclosed herein. For example, in one embodiment, where adjacent bandshave the same number of peaks, facing peaks and troughs which areconnected to one another may abut one another and the connector may bein the form of a small weld or an overlap region between the facing peakand trough. Also, connector which are curved may be used to connectfacing peaks and troughs. The connectors may also be located offset fromthe peaks and troughs.

The invention is also directed to stents such as those disclosed hereinwith sidebranch access. Such a stent may be provided by omitting one ormore struts in one or more desired regions of the stent. Sidebranchaccess may also be provided by omitting a first serpentine band andproviding connectors between some, but not all of the peaks and troughsof the resulting adjacent second serpentine bands. Sidebranch access mayfurther be achieved in any of the inventive stents disclosed herein byalternating the location of connectors between adjacent serpentinebands. For example, where it is desirable to provide for sidebranchaccess, fewer connections between adjacent bands may be provided.Sidebranch access may also be provided by including adjacent serpentinebands of different total pathlength. In such a case, it is desirablealthough not necessary that the adjancent serpentine bands have the samenumber of peaks.

The inventive stents disclosed herein may also be used in bifurcatedstents. The trunk and/or any of the branches may be provided with stentshaving the novel designs disclosed herein.

Any of the inventive stents disclosed above may be provided with auniform diameter or may taper in portions or along the entire length ofthe stent. Also, the width and/or thickness of the various portions ofthe inventive stents may increase or decrease along a given portion ofthe stent. For example, the width and/or thickness of the struts,serpentine bands and/or longitudinal connectors may increase or decreasealong portions of the stent or along the entire length of the stent. Theamplitude and/or wavelength of several successive first serpentine bandsmay remain constant while the width and/or thickness of the successivefirst serpentine bands decreases. Similarly, the amplitude and/orwavelength of several successive second serpentine bands may remainconstant while the width and/or thickness of the successive secondserpentine bands decreases. In other embodiments of the inventive stentsdisclosed herein, the amplitude and/or wavelength of several successivefirst serpentine bands may decrease or increase while the width and/orthickness of the successive first serpentine bands remains constant.Similarly, the amplitude and/or wavelength of several successive secondserpentine bands may or decrease or increase while the width and/orthickness of the successive second serpentine bands remain constant. Theamplitude of the stent could also be increased or decrease along withthe thickness and/or width of the stent.

The inventive stents may be manufactured using known stent manufacturingtechniques. Suitable methods for manufacturing the inventive stentsinclude laser cutting, chemical etching or stamping of a tube. Theinventive stents may also be manufactured by laser cutting, chemicallyetching, stamping a flat sheet, rolling the sheet and welding the sheet,by electrode discharge machining, or by molding the stent with thedesired design.

Any suitable stent material may be used in the manufacture of theinventive stents. Examples of such materials include polymericmaterials, metals, ceramics and composites. Suitable polymeric materialsinclude thermotropic liquid crystal polymers (LCP's). Where the stent ismade of metal, the metal may be stainless steel, cobalt chrome alloyssuch as elgiloy, tantalum or other plastically deformable metals. Othersuitable metals include shape-memory metals such as nickel titaniumalloys generically known as “nitinol”, platinum/tungsten alloys andtitanium alloys. The invention also contemplates the use of more thanone material in the inventive stents. For example, the first serpentineband and the second serpentine band may be made of different materials.Optionally, the connectors may be made of a different material than thefirst and/or second serpentine bands.

The inventive stents desirably are provided in self-expanding form. Tothat end, they may be constructed from shape memory materials includingNitinol. The self-expanding embodiments of the invention allow for acontrolled expansion of the stent as explained below. Typically,self-expanding stents are restrained on a catheter in an unexpandedconfiguration via a sheath. As the sheath is withdrawn, the newly freedportions of the stent will self-expand. Because the peaks within aserpentine cylindrical bands extend to different longitudinal extent,each serpentine circumferential band will be freed from the sheath inseveral waves—the first wave of peaks, corresponding to the longestpeaks will expand first, followed by a wave of peaks which are shorterexpanding until the serpentine is expanded.

The inventive stents may also be provided in balloon expandable form, oras a hybrid, having self-expanding characteristics and balloonexpandable characteristics.

The inventive stents may include suitable radiopaque coatings. Forexample, the stents may be coated with gold or other noble metals orsputtered with tantalum or other metals. The stents may also be madedirectly from a radiopaque material to obviate the need for a radiopaquecoating or may be made of a material having a radiopaque inner core.Other radiopaque metals which may be used include platinum, platinumtungsten, palladium, platinum iridium, rhodium, tantalum, or alloys orcomposites of these metals.

The inventive stents may also be provided with various bio-compatiblecoatings to enhance various properties of the stent. For example, theinventive stents may be provided with lubricious coatings. The inventivestents may also be provided with drug-containing coatings which releasedrugs over time.

The inventive stents may also be provided with a sugar or more generallya carbohydrate and/or a gelatin to maintain the stent on a balloonduring delivery of the stent to a desired bodily location. Othersuitable compounds for treating the stent include biodegradable polymersand polymers which are dissolvable in bodily fluids.

Portions of the interior and/or exterior of the stent may be coated orimpregnated with the compound. Mechanical retention devices may also beused to maintain the stent on the balloon during delivery.

The inventive stents may also be used as the framework for a graft ormay have a liner disposed therein. Suitable coverings and liners includenylon, collagen, PTFE and expanded PTFE, polyethylene terephthalate andKEVLAR, or any of the materials disclosed in U.S. Pat. No. 5,824,046 andU.S. Pat. No. 5,755,770. More generally, any known graft material may beused including synthetic polymers such as polyethylene, polypropylene,polyurethane, polyglycolic acid, polyesters, polyamides, their mixtures,blends, copolymers, mixtures, blends and copolymers.

The inventive stents may find use in coronary arteries, renal arteries,peripheral arteries including illiac arteries, arteries of the neck andcerebral arteries. The stents of the present invention, however, are notlimited to use in the vascular system and may also be advantageouslyemployed in other body structures, including but not limited toarteries, veins, biliary ducts, urethras, fallopian tubes, bronchialtubes, the trachea, the esophagus and the prostate.

The invention is also directed to stent delivery catheters with stentssuch as those disclosed herein disposed about a portion of the catheter.

The invention is also directed to methods of delivering any of thestents disclosed herein. The methods comprise delivering a catheter withan inventive stent disclosed herein disposed thereabout to a desiredbodily location and expanding the stent or allowing the stent to expand.In the latter case, the stent is self-expanding and a sheath whichrestrains the stent is removed from about the stent. As the sheath isremoved, waves of peaks from a given serpentine circumferential band arefreed to self-expand. Upon deployment of the stent, the catheter isremoved from the body.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the claims where the term“comprising” means “including, but not limited to”. Those familiar withthe art may recognize other equivalents to the specific embodimentsdescribed herein which equivalents are also intended to be encompassedby the claims.

In addition to the specific embodiments claimed below, the invention isalso directed to other embodiments having any other possible combinationof the dependent features claimed below. As such, the particularfeatures presented in the dependent claims can be combined with eachother in other manners within the scope of the invention such that theinvention should be recognized as also specifically directed to otherembodiments having any other possible combination of the features of thedependent claims. For instance, for purposes of claim publication, anydependent claim which follows should be taken as alternatively writtenin a multiple dependent form from all prior claims which possess allantecedents referenced in such dependent claim if such multipledependent format is an accepted format within the jurisdiction (e.g.each claim depending directly from claim 1 should be alternatively takenas depending from all previous claims). In jurisdictions where multipledependent claim formats are restricted, the following dependent claimsshould each be also taken as alternatively written in each singlydependent claim format which creates a dependency from a priorantecedent-possessing claim other than the specific claim listed in suchdependent claim below (e.g. claim 3 may be taken as alternativelydependent from claim 2; claim 4 may be taken as alternatively dependenton claim 1, claim 5 may be taken as alternatively dependent from claims1-4, claim 6 may be taken as alternatively dependent from claims 1-5;etc.).

The above Examples and disclosure are intended to be illustrative andnot exhaustive. These examples and this description will suggest manyvariations and alternatives to one of ordinary skill in this art. Allthese alternatives and variations are intended to be included within thescope of the attached claims. Those familiar with the art may recognizeother equivalents to the specific embodiments described herein whichequivalents are also intended to be encompassed by the claims attachedhereto.

1.-42. (canceled)
 43. A stent comprising: at least one circumferentialserpentine band disposed about a longitudinal axis, the serpentine bandcomprising a plurality of struts, adjacent struts connected one to theother, each serpentine circumferential band constructed of a repeatingpattern of struts of at least three different lengths, the serpentineband having alternating peaks and troughs, the serpentine band includingat least three peaks which are circumferentially and longitudinallyoffset from one another.
 44. The stent of claim 43 comprising aplurality of circumferential serpentine bands, adjacent circumferentialserpentine bands connected to one another.
 45. The stent of claim 43wherein adjacent circumferential serpentine bands are connected to oneanother via two or more longitudinal connectors.
 46. The stent of claim45 wherein peaks and troughs which are substantially circumferentiallyaligned prior to expansion of the stent and which are not connected toone another are circumferentially displaced from one another onexpansion of the stent.
 47. The stent of claim 43 wherein the longest ofthe struts is wider than the other struts.
 48. The stent of claim 47wherein the shortest of the struts is narrower than the other struts.49. The stent of claim 43 constructed and arranged to be self-expanding.50. The stent of claim 43 wherein there are more than twocircumferential serpentine bands.
 51. The stent of claim 43 furthercomprising at least one end band, the end band being in the form of aserpentine band, the peaks or troughs of which are all longitudinallyaligned with one another.
 52. The stent of claim 51, wherein the peaksof the at least one end band include short peaks and long peaks, thelong peaks extending distally beyond the short peaks in the at least oneend band.
 53. The stent of claim 52 wherein the long and short peaks ofthe at least one end band are arranged in a repeating pattern of twolong peaks and one short peak.
 54. The stent of claim 51 wherein thetroughs of the at least one end band include short troughs and longtroughs, the long troughs extending proximally beyond the short troughsin the at least one end band.
 55. The stent of claim 54 wherein the longand short troughs of the at least one end band are arranged in arepeating pattern of two short troughs and one long trough.
 56. A stentcomprising: at least two serpentine bands including a first serpentineband and a second serpentine band, each serpentine band havingalternating peaks and troughs, the first serpentine band includingconnected peaks and unconnected peaks, the second serpentine bandincluding connected troughs and unconnected troughs, the peaks of thefirst serpentine band being substantially longitudinally aligned withthe troughs of the second serpentine band when the stent is in anunexpanded state, the connected peaks connected to the connected troughswith connectors, each of the connectors having two ends which aresubstantially circumferentially aligned with one another